1. Field of the Invention
This invention relates to an apparatus and method for recovering oil, grease, and like hydrophobic materials from a water bath. This invention can be used for the recovery of oil, grease, and petroleum products, or for the recovery of cooking (vegetable or animal) oil or grease, or for the recovery and/or purification of hydrophobic materials including solid materials such as lard, bacon fat, and the like. Further, this invention relates to the apparatus and methods of commonly owned U.S. Pat. Nos. 4,051,024 and 4,268,396, each of which being incorporated herein by reference. Familiarity with these patents and the references cited therein is assumed.
2. Description of the Related Art
Lowe U.S. Pat. No. 4,051,024 relates to employing at least one rotatable plastic disk, partly immersed in the contaminated (oil-containing) fluid bath. The disk is rotated at a slow speed and the oil sticks to the disk. A scraper blade removes the oil stuck on the disk and it flows, by gravity, into an oil collector. The disk is motor driven. The accumulating system shown in U.S. Pat. No. 4,051,024 consists of conductor channels which, by gravity, feed the oil to a collector.
In a publicly available embodiment of U.S. Pat. No. 4,051,024, an eccentric was connected to the shaft which rotated the disk. The eccentric drove a pivot arm in an up and down motion to drive the piston of a stroke pump, i.e., the embodiment had a stroke pump. This pump pumped out an oil collector (sump) which collected the oil fed by gravity discharge from the scraper assembly. In this embodiment, the pump needed to be primed and the disk moved slowly; not fast enough to prime the pump. The thought behind making that embodiment of U.S. Pat. No. 4,051,024 was to provide a mechanism to recover oil from oil spills. However, it was learned that for an embodiment of U.S. Pat. No. 4,051,024 to be used with oil spills, required a large disk, 4' to 8' in diameter, and the plastic disc required a metal back-up disk (otherwise the plastic disk would bend and warp). Not only was such an embodiment, big, bulky and plagued with problems, but it was costly and required a large capital investment. Thus, that embodiment was unsuccessful, and is believed to be of no practical utility, although about a handful of such mechanisms may still be in use.
Neither this publicly available embodiment, nor U.S. Pat. No. 4,051,024, teaches or suggests the present invention, particularly, the pump system and the elimination of the sump.
Lowe U.S. Pat. No. 4,268,396 is like U.S. Pat. No. 4,051,024 in some respects. However, U.S. Pat. No. 4,268,396 relates to an oil recovery apparatus and method for use with restaurant dishwashing apparatus. It separated grease and/or oil from the restaurant dishes and/or utensils. In this patent, the disk is also rotated by a motor. As to collection of the recovered grease or oil, this patent merely provides a gravity discharge tube. Since the contaminated fluid in this setting contains debris such as cigarette butts, food particles, and the like, a strainer is provided before the oil recovery bath.
Currently there is much attention being directed to preserving the environment by both social and legal action, e.g., environmental laws and enforcement. For example, commercial quantities of waste liquids often cannot be simply dumped into the public sewer system. Hydrophobic materials (oil and grease) in waste water must be separated from the water. Many local sewer authorities require users to remove hydrophobic materials such as oil and grease from waste water before it is dumped into the sewer system. However, even if the waste oil and grease is separated, often the waste cannot be burned because large amounts of hydrophobic materials are dangerous to incinerators. Further, debris, including sand, silt and the like must also be separated from such waste water and hydrophobic materials.
It is thus desirable to make the apparatus and methods of the aforementioned Lowe et al patents simpler, inexpensive, easier to install, more efficient and easier to perform in order to produce waste water relatively free of oil, grease and debris, so that the waste water may be dumped into a public sewer system. In general, it is desirable to improve the apparatus and methods of the aforementioned Lowe et al Patents. It is further desirable to provide improvements in, inter alia, the collection of the recovered oil or the strainer of the apparatus and methods of Lowe et al. In addition, it is desirable to improve the strainer of Lowe et al so that the apparatus and methods of Lowe et al can be employed for different uses, such as purifying hydrophobic materials.
It is therefore an object of this invention to provide an improved apparatus and method for recovering hydrophobic materials such as oil, grease, etc. from a water bath or pool. It is also an object of this invention to provide improvements on the methods and apparatus of the previous Lowe et al Patents. Further it is an object of this invention to provide an apparatus and method of recovering hydrophobic materials wherein the collection of the recovered materials and the straining of contaminated fluid are improved. It is also an object to provide such an apparatus and method having an improved strainer. Further, it is an object of this invention to provide an improved strainer, which may be used in other devices.